“Yes; not only are you enabled in my air-ship,” continued the Professor, “to travel through space at a rate of speed exceeding that of the fastest steam engines of our time, but you can navigate absolutely at will. The motive power is stored electricity, joined to a new force which I discovered, and which is one of the important features of my invention. I’ll not touch upon the suspensory power,” continued the Professor, launching forth upon his theme with the enthusiasm of the scientist, “for that is too simple. Let me explain to you the combined motor and atmospheric counter resistant forces by which the aërial guidance is ensured. Imagine a central turret--we owe the basic invention on this point to the distinguished scientist Roowalter--a central turret, I say, furnished with powerful concentric screws connected with a number of lateral phalanxes, or----” “Merciful powers, Professor!” cried Kearns, “you make my head swim. Why, man alive, you might as well explain all this to a stone wall as to me, for all I understand of it. Your thing floats and travels fast and can be steered, eh?” “Precisely,” answered the Professor indulgently. “And how big is it?” “You can build it any size you please,” replied the Professor. “It can be built so large as to----” “What is the smallest practical size?” “About as small as an ordinary row-boat, only somewhat deeper and more pointed at the prow.” “It can be made to stand absolutely still in space?” continued Kearns. “Again, I will compare it to a row-boat,” replied the Professor. “If the motor power be shut off it will remain practically still, drifting more or less lightly in the air currents, just as a row-boat, unpropelled by the oars, drifts in the water according as the currents are more or less strong.” “But suppose you could grapple with an anchor or other attachment, to the trunk of a tree, or the side of some structure, would it take much force to hold your machine perfectly still?” questioned Kearns. “Very little,” answered the Professor, “in fact, I can again best illustrate by suggesting a row-boat held steady by a boat-hook.” “Just so,” answered Kearns slowly and with a thoughtful air; “I think I understand. And how long,” he continued, after a moment’s reflection, “would it take you to build a machine of this character?” “Of what size?” “Oh, the smallest size.” “That would depend,” answered the Professor, “upon the facilities at my command. Given a shop fully and efficiently equipped, I could turn out my air-ship in a remarkably short time. Like most good things, it presents the merit of much simplicity after once the right principles have been discovered. You see----” “What do you call a short time,” interrupted Kearns, “assuming you had the highest facilities?” “Oh, I wouldn’t like to specify exactly----” “Tell me,” broke in Kearns impetuously; “would it be a day--a month--a year?”